Process for the manufacture of hard waxes rich in ester from mixtures of montan wax acids and paraffins



. Josef Kaupp and Oswald Metz, Gersthofen,

United States Patent PROCESS FOR THE MANUFACTURE OF HARD WAXES RICH IN ESTER FROM MIXTURES 0F MONTAN WAX ACIDS AND PARAFFINS near Augsburg, Germany, assignors to Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius & Briining, Frankfurt am Main, Germany, a corporation of Germany No Drawing. Filed Apr. 21, 1960, Ser. No. 23,638 Claims priority, application Germany Apr. 25, 1959 8 Claims. (Cl. 106-270) The present invention relates to a process for the manufacture of hard Waxes rich in ester from mixtures of montan wax acids and parafiins.

Various methods are known for converting paraflin hydrocarbons of high molecular weight into ester waxes. In all these processes it is necessary that the parafiin be previously converted into an oxygen-containing compound in order to be rendered partially or completely susceptible to an esterification. For this purpose, the paraffin may be subjected, for example, to an oxidation. As oxidizing agents there are generally used oxygen, air or compounds yielding oxygen, for example nitric acid or nitrous gases. Oxidation products having a particularly high acid content are obtained by a combination of the aforesaid oxidation method with a chromosulfuric acid oxidation. It is also possible to convert par-afiin into carboxylic acids by chlorination, dehydrochlorination, oxo-reaction and subsequent oxidation or alkali melt or direct oxidation of the parafiin dehydrochlorination products. The wax acids so obtained are, however, seldom used per se for the manufacture of high-grade ester waxes, since their hardness is only relatively low and they are often too expensive. As acid components for the esterification there are therefore often used mixtures of montan wax acids and paraflin oxidation products as they are obtained, for example, by treating montan wax and high molecular weight parafiin hydrocarbons oxidized with air, separately or simultaneously with chromosulfuric acid. In all cases, the paraflin is at least partially converted into carboxylic acids in a separate stage prior to the esterification.

Now we have found that hard waxes rich in ester can be obtained in a simple and direct manner from high molecular weight paraflin hydrocarbons having a solid-ifioation point above 70 C. by oxidizing said parafiin hydrocarbons together with montan wax acids in the molten state at temperatures up to 200 C., advantageously within the range of 130 to 170 C., with oxygen or gases containing oxygen, advantageously in the presence of a catalyst. It was surprising to see that the oxidation proceeds in a manner substantially contrary to what would be expected from the oxidation of paraflin with air. Whereas the acid number and ester number increase continuously in the oxidation of parafiin with air, the ester number increases in the oxidation according to the invention while the acid number decreases or remains unchanged and increases only insignificantly in rare instances.

As parafiin components for the compositions to be oxidized by the process of the invention there may be used natural, or advantageously synthetic, paraflin hydrocarbons of high molecular weight whose solidification point is above 70 C., advantageously above 90 C., for example well refined petroleum paraffins or hydrocarbon mixtures obtained in the catalytic carbon monoxide hydrogenation or mixtures containing at most about 40% of wax-like high pressure polyolefins or low pressure polyolefins, for example from ethylene and/or propylene,

which generally have a molecular weight within the range of about 1000 to about 5000 to 10,000.

The montan wax acids used in the manufacture of ester waxes are commercially available Wax acid mixtures as they are obtained, for example, by the oxidation of montan wax with chromic acid. By oxidizing such montan wax acids under the reaction conditions of the present invention, the characteristic values are only insignificantly changed while the oxidation products are strongly discolored.

Parafiin and montan wax acids, mixed in a desired proportion, can be oxidized with oxygen or gases containing oxygen, for example air or air enriched with oxygen. With extreme mixing proportions, the result of the oxidation is influenced by the component constituting the major portion of the mixture. When, for example, and more of the mixture is paraflin, the oxidation substantially proceeds like a normal parafiin oxidation. The mixtures suitably contain about 20 to 80% by weight, advantageously 30 to 70% by weight, of paraflin, the percentage figures being calculated on the total weight of the mixture to be oxidized. In many cases, the mixing proportion depends on the desired acid number of the end product. If it is intended to obtain low acid numbers, a large proportion of paraffin may be used. For high acid numbers, a larger proportion of wax acids must be added. The following table shows how the acid number of the starting mixture decreases as the paraffin content increases, the montan wax acid having an acid number of 150.

20,000, advantageously The oxidation conditions are also variable. The lower limit of the temperature is determined by the melting range of the mixture and the upper limit by the rate of discoloration which increases with the oxidation temperature.- At extremely low temperatures, for example immediately above the melting range of the mixture, in which case longer reaction timesare needed, the acid number is sometimes slightly increased. The oxidation is therefore advantageously carried out at a temperature within the range of and 200 C., advantageously and C.

The laws known from the paraffin oxidation apply also to the oxidation according to the invention. For a fast oxidation, the following factors are of importance: fine distribution of oxidizing agent; quantity of oxidizing agent used per-hour and unit of weight of starting material; contact time; pressure. For example, 200 to 1000 liters of air may be blown in per kilogram of Wax.

It is of advantage to proceed in the presence of a catalyst as it is used in the paraffin oxidation carried out with air, for example a metal salt, heavy metal oxide, or-

ganic peroxide or acid. By the use of such catalyst, the

oxidation is considerably accelerated and the discoloration of the oxidation product shifted towards high degrees of oxidation, as desired. Heavy metal soaps such as the stearate or naphthenate of cobalt or manganese are very effective, especially in the ester formatiou they presence of a catalyst. The oxidation time depends on .the parafiin content of Vthemixture and thedesired degree of oxidation. The latter is defined in a very simple manner by the content of unchanged paraffin. The higher the proportion of paraflin, the longer is the time of oxidation. The oxidation time is limited by the tendency of the oxidation product to deepen in color, since fairly light oxidation products are desired.

As already mentioned above, the process of the invention enables waxes that are rich in ester to be directly obtained by air oxidation of mixtures of high molecular weight paraflin hydrocarbons and montan wax acids. The conversion of the paraffin to oxygen-containing products increases with the oxidation time, the paraffin being incorporated with the wax in the form of ketones and alcohols and predominantly in the form of esters.

The composition of the end products can be varied within wide limits. In mixtures having a high content of parafiin, for example, only a part of the paraffin may be oxidized, whereby especially the long chain paraxfin molecules are reacted. Alternatively, the paraffin may be reacted almost completely, this method being particularly advantageous when mixtures containing a small proportion of paraffin are used. The oxidation products obtained by the process of the invention are somewhat softer than the starting mixture, have a lower melting point and a light yellow to brown coloration depending on the degree of oxidation. They may be used directly or if desired after complete or partial conversion of the free acid groups still present into soaps, amides or esters, for the manufacture of floor polishes and leather dressing agents. Products containing lime soap may also be used as lubricating waxes for the work-up of plastics, the unchanged oxidation products make agents favoring the emulsifica- ,tion of soft paratfins and the amidation products thereof may be used as cable sealing compounds in the electrical industry. It is also possible to admix the products obtained by the process of the invention subsequently with other substances commonly used in wax preparations, for example ester waxes, amide waxes and/ or hydrocarbon waxes.

The following examples serve to illustrate the invention but they are not intended to limit it thereto. The acid number, saponification number, ester number, hydroxyl number and carbonyl number were determined according to the methods usually applied in the analysis of waxes. The flow point/ drop point was determined according to Ubbelohde, the solidification point was determined at a rotating thermometer and the parafiin content of the oxidation products was determined by chromatography. The hardness was measured as penetrorneter hardness (load 100 g.; 5 seconds; 25 0.).

Example 1 A mixture of 240 grams of montan wax acid (acid number 150, saponification number 175, flow point/drop point 80.0/80.5 C.) which had been obtained by subjecting montan wax to an oxidizing bleaching with chromosulfuric acid and 160 grams of a hard paraflin of high molecular weight which had been obtained by synthesis and had a solidification point of 98 C., was oxidized for 9 hours at 150 C. with 200 liters/ hour of air in the presence of 1 grain of cobalt stearate as catalyst in an oil-heated frit tube 500 mm. high and 50 mm. in diameter. The following table indicates the characteristic values of the starting mixture and the oxidation products obtained after 4 hours and 9 hours respectively.

oxidation oxidation Starting product product mixture after 4 after 9 hours hours acid number 92 80 73 saponification number 107 117 133 ester num er 37 60 hydroxyl number 0 16 14 carbonyl number. 10 32 40 flow point/drop point, C. 112. 0/112. 5 101. 5/102 0 95.0195 5 penetrometer number- 1 4 'paraflin content, percent 40 20 10 4 300 grams of the yellow oxidation product were sub sequently reacted within 7 hours at 140 to 160 C. with 15 grams of ethylene diamine. A brown, very hard wax was obtained which had the following characteristic values: acid number 10, saponification number 50, flow point/drop point 102.6/103.0 C., penetrometer hardness 2.

Example 2 A mixture of 160 grams of the montan wax acid described in Example 1 and 240 grams of the hard parafiin described in Example 1 was oxidized at 165 C. for 3.5 hours with 200 liters/hour of air in the presence of 1 gram of cobalt stearate as catalyst in an oil-heated frit tube. The following table indicates the characteristic values of the starting mixture and the oxidation product obtained.

starting oxidation mixture product acid number 61 52 saponification number 72 ester number 11 63 hydroxyl number 0 11 carbonyl number 3 38 flow point/drop point, C- 1140/1145 99.21995 penetrometer number l 3. 5 paraffin content, percent 60 14 250 grams of the dark yellow oxidation product were saponified, while stirring vigorously, within 20 minutes at 110 to C. with 8 grams of calcium hydroxide under a nitrogen atmosphere. The light brown, tough reaction product containing lime soap had the folowing characteristic values: acid number 15, saponification number 75, flow point/ drop point 995/1005 C.

Example 3 Example 4 A mixture of 160 grams of the montan wax acid of Example 1, 204 grams of the hard parafiin of Example 1 and 36 grams of a low pressure polyethylene having a melting point of 118 C. and an average molecular weight of about 2000 was oxidized at C. for 8.5 hours with 200 liters/hour of air in the presence of 1 gram of cobalt stearate as catalyst in the oil-heated frit tube described in Example 1. The following table indicates the characteristic values of the starting mixture and the oxidation product obtained.

starting oxidation mixture product acid number 60 50 saponification number 81 96 ester number 21 46 hydroxyl number 15 carbonyl number 4 31 flow point/drop point, l13.2/113.5 1030/1035 penetrometer number".-- 0. 5 1. 5 paraflin content, percent 60 18 Example 5 starting oxidation mixture product acid number 86 82 saponification number 100 117 ester number 14 35 hydr0xylnun1ber 0 1 carbonyl number 9 23 flow point/drop point, 81.0/81.3 80.6/810 penetrometer number 1 1. 5 paraifin content, percent 40 28 Instead of cobalt stearate, the corresponding naph thenate or the manganese salts of these acids may be used as catalysts.

We claim:

1. A process for the manufacture of a hard wax rich in ester which comprises contacting a molten mixture consisting essentially of (1) a high molecular aliphatic hydrocarbon having a solidification point above 70 C. and (2) a montan wax acid at a temperature up to 200 C. with free oxygen, until at least about 30 percent of the said high molecular aliphatic hydrocarbon is oxidized to form an aliphatic alcohol which reacts with the wax acid to form the ester, the high molecular aliphatic hydrocarbon being contained in the starting mixture in an amount from 20 to 80 percent by weight.

2. A process for the manufacture of a hard Wax rich in ester which comprises contacting a molten mixture consisting essentially of 1) a high molecular aliphatic hydrocarbon having a solidification point above 90 C. and (2) a montan wax acid at a temperature in the range between 130 and 170 C. with free oxygen, until at least about 30 percent of the said high molecular aliphatic hydrocarbon is oxidized to form an aliphatic alcohol which reacts with the wax acid to form the ester, the high molecular aliphatic hydrocarbon being contained in the starting mixture in an amount from 20 to 80 percent by weight.

3. The process of claim 2, wherein the free oxygen is applied in the form of air.

4. The process of claim 2, wherein the free oxygen is applied in the form of air enriched with oxygen.

5. A process as claimed in claim 2, wherein the high molecular aliphatic hydrocarbon contains up to 40 percent of a polymer having a molecular weight in the range between about 1000 and about 20,000, said polymer being a polymer of at least one olefin selected from the group consisting of ethylene and propylene.

6. A process as claimed in claim 2, wherein the starting mixture to be oxidized contains from 30 to percent of a high molecular aliphatic hydrocarbon.

7. A process for the manufacture of a hard wax rich in ester which comprises contacting a molten mixture consisting essentially of (1) a high molecular aliphatic hydrocarbon having a solidification point above 90 C. and (2) a montan Wax acid at a temperature in the range between 130 and 170 C. with free oxygen in the presence of less than 1 percent of an oxidation catalyst, until at least about 30 percent of the said high molecular aliphatic hydrocarbon is oxidized to form an aliphatic alcohol which reacts with the wax acid to form the ester, the high molecular aliphatic hydrocarbon being contained in the starting mixture in an amount from 20 to 30 percent by weight.

8. A process for the manufacture of a hard Wax rich in ester, which comprises contacting a molten mixture consisting essentially of 20 to percent by Weight of a. high molecular aliphatic hydrocarbon having a solidification point above C. and the balance of a montan wax acid at a temperature in the range from to C. with 200 to 1000 liters, calculated per kilogram of the starting mixture, of air, until at least about 30 percent of the said high molecular aliphatic hydrocarbon is oxidized to form an aliphatic alcohol which reacts with the Wax acid to form the ester.

FOREIGN PATENTS Great Britain Jan. 26, 1933 

1. A PROCESS FOR THE MANUFACTURE OF A HARD WAX RICH IN ESTER WHICH COMPRISES CONTACTING A MOLTEN MIXTURE CONSISTING ESSENTIALLY OF (1) A HIGH MOLECULAR ALIPHATIC HYDROCARBON HAVING A SOLIDIFICATION POINT ABOVE 70*C. AND (2) A MONTAN WAX ACID AT A TEMPERATURE UP TO 200*C. WITH FREE OXYGEN, UNTIL AT LEAST ABOUT 30 PERCENT OF THE SAID HIGH MOLECULAR ALIPHATIC HYDROCARBON IS OXIDIZED TO FORM AN ALIPHATIC ALCOHOL WHICH REACTS WITH THE WAX ACID TO FORM THE ESTER, THE HIGH MOLECULAR ALIPHATIC HYDROCARBON BEING CONTAINED IN THE STARTING MIXTURE IN AN AMOUNT FROM 20 TO 80 PERCENT BY WEIGHT. 